• The KIPS Transactions:PartD
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• v.12D no.6 s.102
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• pp.875-880
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• 2005

Recently web services ale being used to provide environments of distributed computing. Web services provide reusable software component. So, one web service can be used by many users, and one user can use different web services. For reliable use of web services, in these cases, it is important to be fault-tolerance. Existing fault-tolerant methods in web services need a kind of client modification and cannot consider extensible factors like quality. This study suggests the system architecture and description language for the system which can improve some of these problems.

• Journal of Internet Computing and Services
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• v.14 no.1
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• pp.31-39
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• 2013

Generally, there can be a interface discrepancy between the legacy hardware and the new software in combining new software component with reused hardware components in the embedded system. This kind of the interface discrepancy may cause various types of faults and also result in declining interface fault tolerance. In this paper we propose a method to improve interface fault tolerance. First of all, the new interface discrepancy fault type which has not been dealt with before is to be defined and next the testing method for generating test paths is proposed by considering the new defined interface discrepancy fault type in this paper. Several tests show that the proposed method detects more fatal faults about 7.9% in comparison with the existing testing method for commercial broadcasting receiver. Since the proposed method can provide software developers with test paths to be available earlier on the software development cycle, in addition, software developers can regard on interface discrepancy fault in advance. Consequently, more efficient test planning can be established to improve the interface fault tolerance.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.760-765
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• 2004

One of the obstacles for a magnetic bearing to be used in the wide range of industrial applications is the failure modes associated with magnetic bearings, which we don't expect for conventional passive bearings. These failure modes include electric power outage, power amplifier faults, position sensor faults, and the malfunction of controllers. Fault-tolerant magnetic bearing systems have been proposed so that the system can operate in spite of some faults in the system. In this paper, we designed and implemented a fault-tolerant magnetic bearing system for a turbo-molecular vacuum pump. The system can cope with the actuator/amplifier faults as well as the faults in position sensors, which are the two major fault modes in a magnetic bearing system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.518-521
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• 2003

A new measurement system was developed by fault diagnosis system for traction motor using current signal analysis. The motor current signature analysis method is used for traction motor fault diagnosis. The diagnosis system program is constructed by artificial neural networks algorithm, those results from the program are used to train neural networks. The trained neural networks have the ability to compute adaptive results for non-trained inputs, and to calculate very fast due to original parallel structure of neural networks with high accuracy within destined tolerance. This system suggested that available test for checking, the probable extent of aging, and the rate of which aging is taking place.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.3
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• pp.382-391
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• 2019

The naval combat system is a distributed system in which various subsystems are integrated and operated together. The integrated management system(IMS) is a software system for systematically and consistently managing the application software which control and operate various devices in such a combat system. Since the malfunction or failure of such an IMS can disable the entire combat system, the IMS is more important than other application software of the combat system. In this paper, we propose a method to guarantee the stable and correct operation of the combat system. To this end, we propose a redundancy scheme composed of one leader and several followers so as to tolerate the failure situation of the IMS. We also propose a leader selection algorithm to select a new leader when the leader fails and can no longer perform its role. To verify the validity of the study, we verify the fault tolerance behavior of the system and the accuracy of the leader selection algorithm.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.886-889
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• 2017

An active Fault Tolerant Model Predictive Control (FTMPC) using Fuzzy scheduler is developed. Fault tolerant Control (FTC) system stages are broadly classified into two namely Fault Detection and Isolation (FDI) and fault accommodation. Basically, the faults are identified by means of state estimation techniques. Then using the decision based approach it is isolated. This is usually performed using soft computing techniques. Fuzzy Decision Making (FDM) system classifies the faults. After identification and classification of the faults, the model is selected by using the information obtained from FDI. Then this model is fed into FTC in the form of MPC scheme by Takagi-Sugeno Fuzzy scheduler. The Fault tolerance is performed by switching the appropriate model for each identified faults. Thus by incorporating the fuzzy scheduled based FTC it becomes more efficient. The system will be thereafter able to detect the faults, isolate it and also able to accommodate the faults in the sensors and actuators of the Continuous Stirred Tank Reactor (CSTR) process while the conventional MPC does not have the ability to perform it.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1371-1373
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• 2005

Nowadays, Intelligent Electronic Devices(IED) are widely used in power system. In order to improve the selectivity, sensitivity, and reliability of the power system composed by IEDs, A new fault tolerant IED system based on agent technique is presented in this paper. in the presented system, different with existing IED systems, the redundancies are drawn out from IED devices, and compose a standby backup system. And those redundancies are not specified to a particular type of IEDs. By using the agent technique, redundancies can download agents to modify their functions to fit different types of IEDs. As a conclusion, the reliability of the presented system is estimated in this paper.

• Smart Structures and Systems
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• v.30 no.5
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• pp.433-446
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• 2022

Despite efforts to reduce unexpected accidents at confined construction sites, choking accidents continue to occur. Because of the poorly ventilated atmosphere, particularly in long, confined underground spaces, workers are subject to dangerous working conditions despite the use of artificial ventilation. Moreover, the traditional monitoring methods of using portable gas detectors place safety inspectors in direct contact with hazardous conditions. In this study, a long-range (LoRa)-based wireless safety monitoring system that features the network organization, fault-tolerant, power management, and a graphical user interface (GUI) was developed for underground construction sites. The LoRa wireless data communication system was adopted to detect hazardous gases and oxygen deficiency within a confined underground space with adjustable communication range and low power consumption. Fault tolerance based on the mapping information of the entire wireless sensor network was particularly implemented to ensure the reliable operation of the monitoring system. Moreover, a sleep mode was implemented for the efficient power management. The GUI was also developed to control the entire safety-monitoring system and to manage the measured data. The developed safety-monitoring system was validated in an indoor testing and at two full-scale water pipeline construction sites.

• International Journal of Control, Automation, and Systems
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• v.4 no.1
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• pp.105-112
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• 2006

The main function of a reactor protection system is to maintain the reactor core integrity and the reactor coolant system pressure boundary. Generally, the reactor protection system adopts the 2-out-of-m redundant architecture to assure a reliable operation. This paper describes the safety assessment of a digital reactor protection system using the fault tree analysis technique. The fault tree technique can be expressed in terms of combinations of the basic event failures such as the random hardware failures, common cause failures, operator errors, and the fault tolerance mechanisms implemented in the reactor protection system. In this paper, a prediction method of the hardware failure rate is suggested for a digital reactor protection system, and applied to the reactor protection system being developed in Korea to identify design weak points from a safety point of view.

• The Transactions of the Korea Information Processing Society
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• v.6 no.2
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• pp.326-334
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• 1999

There are the fault tolerance technology and the fault avoidance technology to analyze and evaluate the performance of computer system. To improve the relibility of software The N-Version Programming (NVP) technology is known to be the most objective and quantitive. However, when discrete probability distribution is used as estimation model, the values of it's component reliability should be same. In this paper, to resolve this problem, we adapted the genetic algorithms to NVP technology and implement the optimized simulate. and the results were analyzed and estimated. Through this study, we could optimize the reliability of each component and estimate the optimum count in the system reliability.